The flyback transformer is the core of the flyback switching power supply. It determines a series of important parameters of the flyback converter, such as duty cycle d, maximum peak current, and the design of the flyback transformer is to make the flyback switching power supply work at a reasonable working point. This minimizes heat generation and minimizes wear and tear on the device. The same chip, the same core, if the transformer design is unreasonable, the performance of the entire switching power supply will be greatly reduced, such as the loss will increase, the maximum output power will also decrease, today we will learn the method of designing the transformer.
To design a transformer, it is necessary to first select a working point, at which this point is the lowest AC input voltage, corresponding to the maximum output power. Let's calculate a power supply with an input of 85V to 265V and an output of 5V, 2A, with a switching frequency of 100kHz.
Step 1: Select the primary-side induced voltage vor
Step 2: Determine the parameters of the primary current waveform.
Step 3: Select the transformer core.
Step 4: Calculate the number of primary turns of the transformer.
Step 5: Determine the number of parametric turns and wire diameter of the secondary winding.
Step 6: Determine the parameters of the feedback winding.
Step 7: Determine the amount of inductance.
Step 8: Verify the design.
Summary.
When designing a high-frequency transformer, there are several parameters that need to be set by yourself, and these parameters determine the working mode of the switching power supply. The first is to set the maximum duty cycle d, which is determined by the induced voltage vor that you set. Then the waveform of the primary current is set, the value of KRP is determined, and when the transformer is designed, the core amplitude b is also set, which is another setting.
All these settings make this switching power supply work in the way you set it. To constantly adjust to make it work in the best state for you, this is the design task of high-frequency transformers.
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